Refrigerating apparatus



Oct. 25, 1932. J. H. SHEATS REFRIGERATING APPARATUS Filed Sept. 27, 1929 BY W, M E ATTORNEY Patented Oct. 25, 1932 UNITED STATES PATENT OFFICE JOHN H. SHEATS, OF DAYTON, OHIO, ASSIGNOR TO FRIGIDAIRE CORPORATION, OF

DAYTON, OHIO, A CORPORATION OF DELAWARE REFRIGERATING APPARATUS Application filed September 27, 1929. Serial No. 395,568.

This invention relates to refrigerating apparatus and particularly to apparatus for returning oil from the evaporator to the compressor of a refrigerating system.

One of the objects of the invention is to provide means whereby there is not an excess of oil in the evaporator of a refrigerating system.

Another object of the invention is to provide an oil pocket associated with the evaporator and also so locating this oil pocket whereby any liquid refrigerant therein will be vaporized.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a pre; ferred form of the present invention is clearly shown.

In the drawing:

Fig. 1 is a cross section through an evaporator illustrating an application of the invention;

Fig. 2 is a cross section through a preferred form of cabinet to which the invention has been applied, and

Fig. 3 is a cross section on line 3-3 of Fig). 1.

ne of the problems in connection with a 80 refrigerating system is that of the circulation through the system of the lubricant supplied to the compressor for its necessary lubrication of moving parts. The vaporized refrigerant is generally drawn to the compressor by suction created by a pumping action in the compressor and on being compressed, is forwarded under pressure to the other elements of the refrigerating system. This process of suction, compressing and forwarding by pressure is apt to churn the oil into a foamy state and to carry a certain portion of it to other parts of the refrigerating system where it is not desired. Furthermore, as the compressor generally has the pumping action referred to, a certain portion of the oil is mechanically carried along with and absorbed by the refrigerant. This oil I eventually reaches the evaporator and. where a refrigerant such as sulphur dioxide is used, the oil will form a blanket on the top of the liquid refrigerant in the evaporator or expander.

If too much oil is drawn from the compressor it may result in the moving parts of the compressor being damaged for want of suiii- 6b cient lubrication. If the oil blanket becomes very thick on the surface of the liquid refrigerant in the evaporator it decreases the efficiency of the apparatus by taking the place of the liquid refrigerant and furthermore by hindering the suitable rate of vaporizat-ion of the liquid refrigerant. Accordingly it is one of the objects of this invention to provide means for returning any excessive oil in the evaporator to the compressor.

It is desired however to prevent any liquid refrigerant from also returning with the oil and causing the frosting over of the conduits between the evaporator and the compressor besides preventing the loss of efliciency due 7 to this liquid refrigerant not being evaporated or vaporized in the evaporator.

In Fig. 1 is disclosed a type of evaporator embodying a preferred application of the invention. This evaporator generally referred to by the numeral 10, is preferablyof theflooded float control type more particularly describedinthe patent toR.G.Osborn,1,556,708, issued October 13, 1925. This evaporator is preferably located in the upper portion of so a cabinet such as that disclosed in Fig. 2. This cabinet has the usual outer coating 11 such as steel covered with porcelain or pyroxylin paint enclosing an upper insulated compartment 12 having the easily cleaned lining 13 preferably of porcelain. This compartment is preferably insulated by means of insulation such as the slabs of rock cork 14 suitably sealed to and between the outer coating 11 and inner coating 13 with a bituminous cement such as hydrolene. In the lower portion of the cabinet is preferably a machine compartment 15 in which is located the refrigerant liquefying unit. This refrigerant liquefying unit is preferably composed of the compressor 16, condenser 17 receiver 18 of any suitable construction. The compressor 16 is adapted to withdraw the vaporized refrigerant from the evaporator 10 by suction means and after compressing pressure side of the system.

the same to forward it to the condenser 17 where it is liquefied and deposited in the receiver 18 until required by the evaporator 10. A pressure temperature responsive means 19 automatically controls the motor 20 for running the compressor in response to the temperature conditions within the evaporator 10.

From the head of the compressor through the condenser, receiver and connections to the inlet valve 41 for the liquid refrigerant on the evaporator, the path is called the high The evaporator and connections to the crank case of the cord pressor are called the low pressure side of the system.

As the liquid refrigerant in the evaporator 10 absorbs heat through its walls such as the wall of the tank 21 or the ducts 22, the air surrounding this evaporator is chilled and, being chilled naturally descends downward- 1y. In the type of cabinet illustrated, this downward descent is through an opening 23 in a partition 24:, partitioning off the evap orator from the rest of the compartment. This chilled or cold air passes downwardly over the food or other substances located in the lower part of the insulated compartment and upon being actuated by still more cold air descending from the evaporator and also upon being warmed by the absorption of heat from the articles over which it passes or by the absorption of heat that might have leaked into the cabinet, it passes gradually upward until it reaches the upper portion of the cabinet on the side opposite the evaporator. By the further descent of cold air from the evaporator, this warmer air is again drawn over the surface of the evaporator and again cooled. In other words the evaporator by its cooling effect provides a means for circulating the air about the cabinet and providing efiicient means for maintaining the compartment at a temperature to prevent the food therein from spoiling. The path of this circulation is illustrated by the arrows in Fig. 2.

As the warmer air is drawn over the evaporator the liquid refrigerant 26 located in the evaporator absorbs this heat and vaporizes and passes through an outlet in the form of a pipe 27 in the head 28 of the boiler which connects with a duct 29 for return of gaseous refrigerant to the compressor. The action of the compressor however, as previously explained, is apt to send a lubricant such as oil along with the liquid refrigerant to the evaporator and where a refrigerant such as sulphur dioxide is used, this oil will form an oil blanket 30 on the surface of the liquid refrigerant in the evaporator.

As long as this oil blanket is of a maximum thickness substantially anywhere from to as of an inch in the type of evaporator disclosed it will not seriously effect the action of the evaporator. If, however, this oil blanket reaches a thickness of of an inch it begins to very materially affect the eficiency of the evaporator as the thickness of the oil blanket increases over this of an inch. Accordingly it is very desirable, if not essential, to provide means for returning this oil to the compressor when the thickness of the oil blanket reaches this thickness of if not before.

A preferred type of this oil return means is disclosed in Fig. 1. It is preferred to have one or more walls or partitions such as '32 located in or associated with the evaporator to form an oil pocket 33 therein. The position of the upper edge 34 of this wall or enclosure is of such a height that oil will flow into the pocket or skimmer when a thickness is attained beyond which an increase is not desired. The limit will usually be where the efficiency of the evaporator will soon be affected. It will be desirable in the construction disclosed to have this so that the oil blanket will not exceed approximately in thickness. The wall or walls 32 forming this enclosure are preferably curved upwardly and outwardly to prevent any bubbling of the liquid refrigerant into the oil pocket or skimmer. In other words, any bubbling of the liquid refrigerant strikin against the curved side 32 will be deflected towards the center of the evaporator away from the open top of the oil pocket or skimmer 33. The end walls 34 and 35 of the oil pocket are similarly curved for a like reason. The length and size of this oil pocket is of course a matter of choice and it may even extend the full length of the evaporator, if desired. A conv duit 36 preferably connects the oil ocket or skimmer 33 with the outlet pipe 2 for the vaporized refrigerant.

It is preferred to have this outlet pipe 27 have a constricted part 38 to form a venturi at approximately the place of juncture of the conduit 36 with the outlet pipe 27. By the added suction of this Venturi means the oil in the oil pocket or skimmer 33 is very quickly and positively drawn up the conduit 36 to join with the vaporized refrigerant in its return path to the compressor.

Although the curved walls 32 are adapted to prevent any liquid refrigerant from boiling or otherwise reaching the oil pocket 33 to provide against any possible loss of efficiency due to such liquid refrigerant reaching the oil pocket, the oil pocket or skimmer is preferably located at a point 40 on the surface of the evaporator where the warmer air of the cabinet first strikes the evaporator. In this way if any liquid refrigerant is in the interior of the evaporator it will be very quickly boiled off by the thermal contact of this oil pocket or skimmer with the warmer air. In this manner liquid refrigerant will not be sucked up through the conduit 36 after reaching the oil pocket or skimmer 33. This location of the oil pocket is very desirable if the walls 32 are not curved.

It is obvious that many changes could be made in the preferred form of the invention that this application has disclosed and es pecially the shape of the oil pocket or skim.

mer is subject to wide variation. It might for instance form a tube or conduit to project into the path of the warmer air as it strikes the evaporator. In other words, a short tube may project outwardly from the oil pocket 33. Furthermore, the oil may pass through the head of the evaporator by a path other than that associated within the outlet 27.

Accordingly there has been disclosed a very efficient means for preventing the oil blanket in the evaporator from becoming of such a thickness as to interfere with the efficiency of the evaporator and for also returning this oil to the compressor where it is needed.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. An evaporator adapted to contain a quantity of liquid refrigerant and a layer of oil on the refrigerant, a duct for conveying gas from the evaporator to a compressor, a skimmer within the evaporator having its inlet above the refrigerant level, duct means for conveying oil from the skimmer to the duct, said skimmer having a substantial portion thereof in intimate heat exchange relation with the medium to be cooled by the evaporator.

2. An evaporator adapted to contain a quantity of liquid refrigerant and a layer of oil on the refrigerant, a duct for conveying gas from the evaporator to a compressor, a skimmer within the evaporator having its inlet above the refrigerant level, duct means for conveying oil from the skimmer to the duct, one wall of said skimmer comprising a wall of the evaporator, and said Wall being arranged in intimate heat exchange relation with the medium to be cooled by the evaporator.

3. An evaporator adapted to contain a quantity of liquid refrigerant and a layer of oil on the refrigerant, a gas outlet for the evaporator having its inlet in the free space above the liquid level in the evaporator, a skimmer arranged in intimate heat exchange relation to the medium to be cooled by the evaporator, said skimmer having its interior portion in intimate heat exchange relation with a wall of the evaporator, a conduit con necting the skimmer with the gas outlet for quantity of liquid refrigerant and a layer of oil on the refrigerant, a gas outlet for the evaporator having its inlet in the free space above the liquid level in the evaporator, a skimmer within the evaporator, aconduit connecting the skimmer with the outlet for delivering oil to the latter, one wall of said skimmer comprising a wall of the evaporator, and said wall being arranged in intimate heat exchange relation with the medium cooled by the evaporator.

5. An evaporator adapted to contain a quantity of liquid refrigerant and a layer of oil on the refrigerant, a gas outlet for the evaporator having its inlet in the free space above the liquid level in the evaporator, the passage in said outlet having a portion reduced in cross-sectional area, a skimmer arranged in intimate heat exchange relation with a wall of said evaporator and with the medium to be cooled by the evaporator, and a conduit connecting the skimmer with the reducer portion of the outlet.

6. An evaporator adapted to contain a quantity of liquid refrigerant and a layer of oil on the refrigerant, a gas outlet for the evaporator having its inlet in the free space above the liquid level in the evaporator, the passage in said outlet having a portion reduced in cross-sectional area, a skimmer within the evaporator, one wall of said skimmer comprising a wall of the evaporator, said wall being arranged in intimate heat exchange relation with the medium cooled by the evaporator, and a conduit connecting the skimmer with the reduced portion of the outlet.

7. An evaporator adapted to contain a quantity of liquid refrigerant and a layer of oil on the refrigerant, a gas outlet for the evaporator having its inlet in the free space above the liquid level in the evaporator, the passage in said outlet having a portion reduced in cross-sectional area, a skimmer within the evaporator having its inlet above the refrigerant level, said skimmer having a substantial portion thereof in heat exchange relation with the medium cooled by the evaporator, and a conduit connecting the skimmer with the reduced portion of the outlet.

8. An evaporator adapted to contain a quantity of liquid refrigerant and a layer of oil on the refrigerant, a gas outlet for the evaporator having its inlet in the free space above the liquid level in the evaporator, a skimmer within the evaporator having its inlet above the refrigerant level, said skimmer having a substantial portion thereof in heat exchange relation with the medium cooled by the evaporator, a conduit connecting the skimmer with the gas outlet for delivering oil to the latter, and means within the evaporator for preventing the refrigerant from rising above a certain level in the evaporator.

9. An evaporator adapted to contain a quantity of liquid refrigerant and oil, said evaporator having an outlet for gaseous refrigerant, means for removing oil from the liquid refrigerant and collecting same out of contact therewith, means connectin said first named means with said outlet, sai first named means being continuously open With the free space above the liquid refrigerant and oil in the evaporator and having a portion thereof in intimate heat exchange relation with the medium to be cooled by the evaporator.

10. An evaporator adapted to contain a quantity of liquid refrigerant and oil, said evaporator having an outlet for gaseous refrigerant, means Within the evaporator for removing oil from the liquid refrigerant and collecting same out of contact therewith, conduit means connecting said first named means With said outlet, said first named means having a portion thereof in intimate heat exchange relation With the medium to be cooled by the evaporator.

In testimony whereof I hereto affix my sig nature.

JOHN H. SHEATS. 

